propertyfile.java

FuncPlotter is a combined Java application and applet for displaying two-dimensional plots of explic

/*====================================================================*\

PropertyFile.java

Property file class.

------------------------------------------------------------------------

This file is part of FuncPlotter, a combined Java application and applet
for plotting explicit functions in one variable.
Copyright 2005-2007 Andy Morgan-Richards.

FuncPlotter is free software: you can redistribute it and/or modify it
under the terms of the GNU General Public License as published by the
Free Software Foundation, either version 3 of the License, or (at your
option) any later version.

This program is distributed in the hope that it will be useful, but
WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
General Public License for more details.

You should have received a copy of the GNU General Public License along
with this program.  If not, see <http://www.gnu.org/licenses/>.

\*====================================================================*/


// PACKAGE


package xml;

//----------------------------------------------------------------------


// IMPORTS


import exception.AppException;
import exception.FileException;
import exception.UrlException;

import java.io.File;
import java.io.IOException;

import java.net.URL;

import org.w3c.dom.Document;
import org.w3c.dom.Element;

//----------------------------------------------------------------------


// PROPERTY FILE CLASS


public class PropertyFile
    implements XmlFile.ElementWriter
{

////////////////////////////////////////////////////////////////////////
//  Constants
////////////////////////////////////////////////////////////////////////

    private interface AttrName
    {
        String  VALUE   = "value";
        String  VERSION = "version";
    }

    private static final    String  FILE_STR    = "file";

////////////////////////////////////////////////////////////////////////
//  Enumeration types
////////////////////////////////////////////////////////////////////////


    // ERROR IDENTIFIERS


    private enum ErrorId
        implements AppException.Id
    {

    ////////////////////////////////////////////////////////////////////
    //  Constants
    ////////////////////////////////////////////////////////////////////

        INCORRECT_FILE_FORMAT
        ( "The %1 is not in the correct format." );

    ////////////////////////////////////////////////////////////////////
    //  Constructors
    ////////////////////////////////////////////////////////////////////

        private ErrorId( String message )
        {
            this.message = message;
        }

        //--------------------------------------------------------------

    ////////////////////////////////////////////////////////////////////
    //  Instance methods : AppException.Id interface
    ////////////////////////////////////////////////////////////////////

        public String getMessage( )
        {
            return message;
        }

        //--------------------------------------------------------------

    ////////////////////////////////////////////////////////////////////
    //  Instance variables
    ////////////////////////////////////////////////////////////////////

        private String  message;

    }

    //==================================================================

////////////////////////////////////////////////////////////////////////
//  Constructors
////////////////////////////////////////////////////////////////////////

    public PropertyFile( )
    {
    }

    //------------------------------------------------------------------

    public PropertyFile( String rootElementName )
        throws AppException
    {
        document = XmlUtilities.createDocumentBuilder( false ).newDocument( );
        document.appendChild( document.createElement( rootElementName ) );
    }

    //------------------------------------------------------------------

    public PropertyFile( String rootElementName,
                         String versionStr )
        throws AppException
    {
        this( rootElementName );
        document.getDocumentElement( ).setAttribute( AttrName.VERSION, versionStr );
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Instance methods : XmlFile.ElementWriter interface
////////////////////////////////////////////////////////////////////////

    public void writeElement( XmlWriter writer,
                              Element   element,
                              int       indent )
        throws IOException
    {
        writer.writeElementNoText( element, indent );
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Instance methods
////////////////////////////////////////////////////////////////////////

    public void read( File   file,
                      String rootElementName )
        throws AppException
    {
        try
        {

            // Read document

            document = XmlFile.read( file );

            // Validate name of root element

            if ( !document.getDocumentElement( ).getNodeName( ).equals( rootElementName ) )
                throw new FileException( ErrorId.INCORRECT_FILE_FORMAT, file );

        }
        catch ( AppException e )
        {
            e.setSubstitutionString( getFileTypeString( ) );
            throw e;
        }

    }

    //------------------------------------------------------------------

    public void read( URL    url,
                      String rootElementName )
        throws AppException
    {
        try
        {

            // Read document

            document = XmlFile.read( url );

            // Validate name of root element

            if ( !document.getDocumentElement( ).getNodeName( ).equals( rootElementName ) )
                throw new UrlException( ErrorId.INCORRECT_FILE_FORMAT, url );

        }
        catch ( AppException e )
        {
            e.setSubstitutionString( getFileTypeString( ) );
            throw e;
        }

    }

    //------------------------------------------------------------------

    public void write( File file )
        throws AppException, IllegalStateException
    {

        // Test for document

        if ( document == null )
            throw new IllegalStateException( );

        // Write file

        try
        {
            XmlFile.write( file, document, this );
        }
        catch ( AppException e )
        {
            e.setSubstitutionString( getFileTypeString( ) );
            throw e;
        }

    }

    //------------------------------------------------------------------

    public String getVersionString( )
    {
        return XmlUtilities.getAttribute( document.getDocumentElement( ), AttrName.VERSION );
    }

    //------------------------------------------------------------------

    public String getValue( String elementPath )
    {
        return getValue( elementPath, -1 );
    }

    //------------------------------------------------------------------

    public String getValue( String elementPath,
                            int    index )
    {
        Element element = XmlUtilities.findElement( document, elementPath, index );
        return ( (element == null ) ? null : XmlUtilities.getAttribute( element, AttrName.VALUE ) );
    }

    //------------------------------------------------------------------

    public boolean setValue( String elementPath,
                             String value )
    {
        return setValue( elementPath, -1, value );
    }

    //------------------------------------------------------------------

    public boolean setValue( String elementPath,
                             int    index,
                             String value )
    {
        boolean result = false;
        if ( value != null )
        {
            Element element = XmlUtilities.findElement( document, elementPath, index, true );
            if ( element != null )
            {
                element.setAttribute( AttrName.VALUE, value );
                result = true;
            }
        }
        return result;
    }

    //------------------------------------------------------------------

    protected String getFileTypeString( )
    {
        return FILE_STR;
    }

    //------------------------------------------------------------------

////////////////////////////////////////////////////////////////////////
//  Instance variables
////////////////////////////////////////////////////////////////////////

    private Document    document;

}

//----------------------------------------------------------------------